324 MR. 0. A. SHRUBSOLE ON TRIASSIC PEBBLES OP [Aug. I903, 



an examination of surface-drift, which consists practically of re- 

 arranged Bunter pebbles, at two points on the Lickey : — 



Near Near 



Station. Church. 



Quartz-conglomerate or breccia 2 



Vein-quartz 11 18 



Quartzite, purple and brown 50 51 



Quartzite of various colours 21 11 



Quartzite, green 3 2 



Purple and other grit 6 8 



Other rocks 9 4 



Subangular material (Drift) 4 



100 100 



The Bunter Conglomerate in England can nowhere be said to be 

 a heterogeneous deposit. Two cartloads of pebbles taken from 

 different sections, or even from the same section, would doubtless be 

 found to differ slightly ; but the difference is within fixed limits, 

 and the analysis tabulated above may be taken to represent the 

 type of large material in a general way, whether in Derbyshire, 

 Staffordshire, Worcestershire, or Devon. This general resemblance 

 was noted by Mr. Ussher T as being ' abnormally striking.' It is 

 significant, both in regard to what is included and what is absent 

 or present only in moderate quantity. The proportion of hard 

 sedimentary rocks more or less metamorphosed is very high, and 

 there is only an extremely moderate percentage of vein-quartz. This 

 agrees very well with the Gres de May and the Gres Armoricain 

 of Normandy, in which quartz-veins are not common. There are, 

 moreover, always a few comparatively-soft reddish sandstones ; and 

 these agree in appearance with the softer beds in the Gres de May. 



The pebbles, on the whole, are rounded, yet not always so com- 

 pletely rounded as to have lost all trace of angularity. Even in the 

 Thames quartzite-gravel, where it must have had a further journey 

 of 60 or 70 miles, I have picked up a subangular fragment of red 

 quartzite. In the north-west, as is well known, the pebbles become 

 smaller and more rounded, and are more largely composed of vein- 

 quartz. 



Eor the purpose of comparison with the Normandy rocks, I sub- 

 mitted to Prof. Bonney certain specimens of Bunter pebbles — two 

 from an undisturbed section at Eepton, and three from the valley- 

 gravel at Reading. The last-mentioned were included, because there 

 is strong evidence which justifies us in believing that such pebbles 

 of the characteristic liver-coloured type have been derived from the 

 waste of the Bunter Conglomerate ; and it was desirable to confirm 

 this, as far as it is possible to do so, by microscopic examination. 



Prof. Bonney reports on these specimens as follows : — 



'No. 4. Repton. 

 ' Hand -specimen. — The usual "Torridonian " of the Midland pebbles. 

 'Microscopic characters. — As usual, but little better preserved than 



1 Quart. Journ. Geol. Soc. vol. xxxiv (1878) p. 464. 



